Ink cartridges typically are provided with an ink chamber for storing an ink for ink-jet recording. The ink cartridge typically is detachably installed in an ink-jet recording device. Most ink cartridges accommodate a foam or a porous body having the ability to absorb and hold ink to prevent the leakage of ink from an ejection nozzle of a recording head and to prevent fluctuation of ink liquid level caused by carriage vibration. Foams made of a polymer resin, for example, can be placed within an ink chamber to reduce ink pressure in the ejection nozzle relative to atmospheric pressure (See U.S. Pat. Nos. 6,502,931 and 6,758,557). Polyurethane foams are comparatively easy for controlling the expansion and are inexpensively available.
Solvent dyes have been used in ink-jet recording for improving color developing properties and water resistances of an ink-jet recorded image. One such solvent dye has the structure represented by Formula (1) in which a 9-position of a xanthene structure and a 3-position of a phthalide structure are spiro bound to each other. The dye provides good color developing properties and water resistance.
wherein each R1 independently represents a hydroxyl group or a group represented by Formula (2); and each R2 independently represents a hydrogen atom or a halogen atom.
wherein each R3 and R4 independently represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms.
When an ink containing a solvent dye of Formula (1) is filled in an ink chamber of having a polyurethane foam and is allowed to stand for a prolonged time, the image quality of printed material obtained by ink-jet recording may be reduced. It is believed that the dye is adsorbed into the polyurethane foam due to interaction between the solvent dye and the polyurethane foam, which in turn may lower printing density and change hue.